re:
> HOx isn't one of the tests, it must have been either NOx (nitrogen oxides) or
>HC
> (hydrocarbons).
Good point. I assumed he meant hydrocarbons since the California test only
allows
about 400ppm NOx. My SO's Country failed smog due to NOx, I put a new cat on
(per the tester's recommendation) only to remember that NOx is usually caused by
the EGR system. It barely passed with the new cat; I'll need to check the EGR
system before the next test.
On this car (4.0L 6-cyl), the EGR involves a temp switch, a vacuum modulator for
the EGR valve and the EGR valve itself, any of which can fail.
bs
***************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
***************************************************************
Subject: RE: Questions on Emissions
>
>> The failure was for high HOx levels. 1057 was the limit and she was at
>> 1345 (from memory)
>
> HOx isn't one of the tests, it must have been either NOx (nitrogen oxides) or
>HC
> (hydrocarbons). A NOx failure indicates the EGR valve isn't working (bad
>valve,
> plugged passages, broken/cracked vacuum line, etc.) or possibly engine knock
> (due to advanced ignition or poor fuel). Might be a cat failure if your
>engine
> has a "3-way" cat.
>
> High HC (without other failures) generally indicates the engine is misfiring
>due
> to poor ignition or whatever (lean mixture if CO is unusually low), but might
> also indicate the cat is bad. High HC will eventually make the cat fail from
> overheating, so it may be bad now even if it's not the root problem.
>
> Randall
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